Wetzel, C. E.; Van de Vijver, B.; Kopalová, K.; Hoffmann, L.; Pfister, L. ; Ector, L. (2014). Type analysis of the South American diatom Achnanthes haynaldii (Bacillariophyta) and description of Planothidium amphibium sp. nov., from aerial and aquatic environments in Oregon (USA).
Plant Ecology and Evolution. 147(3): 439-454.